In the advancing semiconductor manufacturing industry, new substrate materials are being developed in response to the demand for greater electron and hole mobility and work function tuning. Materials such as germanium, SiGe and Group III-V materials such GaAs, InP and InGaAs are being proposed because of their lattice structures and inherent stresses which have been found to enhance electron and hole mobility in integrated circuit and other semiconductor devices. The use of these materials is particularly advantageous as device processing technologies continue to advance and devices are formed in the 10 nanometer regime.
A challenge faced in the development of these new materials as channel substrate materials lies in the incompatibility between the new channel substrate materials and conventional wet chemical processes used in semiconductor manufacturing. Wet chemical cleaning operations are commonly used in semiconductor manufacturing for various purposes including the cleaning operations that follow dry photoresist stripping operations. Wet chemical operations are also used to remove oxide layers and for other purposes. Wet chemical operations are typically used multiple times in the sequence of processing operations used to manufacture a semiconductor device. Commonly used chemicals used for wet chemical processing operations include HCl, HF, HNO3, H2SO4, NH4OH, APM, HPM and Caros acid (SPM). Additional chemicals are also used in other conventional wet chemical processing operations.
The new substrate materials such as Ge, SiGe and Group III-V materials are susceptible to attack by these wet chemicals used in semiconductor manufacturing. The wet chemical processing operations induce a significant amount of substrate film loss and also damage the substrate materials by roughening the surfaces to unacceptable levels. This undesirable surface morphology adversely affects subsequent processing operations.
It would therefore be desirable to formulate processing operations that are compatible with the new substrate materials that provide the aforementioned advantages.